On 9/11/13 11:49 AM, Eric Sandeen wrote:

On 9/11/13 6:30 AM, Theodore Ts'o wrote:

quoted

On Tue, Sep 10, 2013 at 10:13:16PM -0500, Eric Sandeen wrote:

quoted

Above doesn't tell us the prevalence of various contexts on the actual system,
but they are all under 100 bytes in any case.

OK, so in other words, on your system i_file_acl and i_file_acl_high
(which is where we store the block # for the external xattr block),
should always be zero for all inodes, yes?

Oh, hum - ok, so that would have been the better thing to check (or at
least an additional thing).

# find / -xdev -exec filefrag -x {} \; | awk -F : '{print $NF}' | sort | uniq -c

Finds quite a lot that claim to have external blocks, but it seems broken:

# filefrag -xv /var/lib/yum/repos/x86_64/6Server/epel
Filesystem type is: ef53
File size of /var/lib/yum/repos/x86_64/6Server/epel is 4096 (1 block, blocksize 4096)
 ext logical physical expected length flags
   0       0 32212996252             100 not_aligned,inline
/var/lib/yum/repos/x86_64/6Server/epel: 1 extent found

So _filefrag_ says it has a block (at a 120T physical address not on my fs!)

Oh, this is the special-but-not-documented "print inline extents in bytes
not blocks"  :(

I'll send a patch to ignore inline extents on fiemap calls to make this
easier, but in the meantime, neither my RHEL6 root nor my F17 root have
any out-of-inode selinux xattrs on 256-byte-inode filesystems.

So selinux alone should not be exercising mbcache much, if at all, w/ 256 byte
inodes.

-Eric